Administration of the MapR Database is done primarily via the command line (maprcli) or with the MapR Control System (MCS). Regardless of whether the MapR Database table is used for binary files or JSON documents, the same types of commands are used with slightly different parameter
options. MapR Database administration is associated with tables, columns and column families, and table regions.

The MapR Data Access Gateway is a service that acts as a proxy and gateway for translating requests between lightweight
client applications and the MapR cluster. This section describes considerations when upgrading the service, how to modify
configuration settings, and how to administer and manage the service.

Managing Extended Attributes

Extended attributes (referred to as xattrs) allow user applications to associate additional
metadata with a regular file or directory. Unlike system-level inode metadata, such as file
permissions or modification time, extended attributes are not interpreted by the system and
are instead used by applications to store additional information about an inode. Multiple
extended attributes can be associated with a single inode. The maximum size allowed for an
extended attribute is 64 KB.

An extended attribute is a name-value pair, with a string name and binary value. The extended
attribute names are prefixed with a namespace. For example, an xattr named myXattr in the user
namespace would be specified as user.myXattr.

Limitations

For the five valid namespaces supported by HDFS, MapR supports the following:

Namespace

MapR Functionality

user

Commonly used by client applications. Access to these extended attributes
in the user namespace is controlled by corresponding file/directory permissions.
For more information, see Permissions for Extended Attributes.

trusted

Available to superusers only. Access is denied for all other users. The
extended attribute is not available through userspace methods.

Note: The raw namespace is not supported by
MapR.

Extended attributes cannot be associated with symbolic links. If extended attributes
are used on symbolic links, they are instead applied to the symbolic link target file.

The preserve options of commands like cp -px and distcp
-px will work on extended attributes only in the following cases:

With Hadoop commands such as hadoop fs.

On FUSE mounted file paths.

Note: Extended attributes are not supported on NFS file paths.

Permissions for Extended Attributes

The following table lists the permissions (POSIX mode bits or ACEs) you will need to set,
retrieve, or modify extended attributes.